I can't figure out the date of manufacture of this monster, other than placing it sometime in the 1970s; this Apollo fan site provides some history for you vintage RV buffs. Apparently the Chrysler 440 was a popular engine for Apollos, but I must assume that one this big requires the torque of a diesel to get it rolling.
As for rolling, this Apollo seems to be undergoing some sort of restoration. It's a newcomer to the neighborhood, so it stands to reason that it drove here under its own power... or maybe it was dragged in behind a tow truck, much to the horror of the neighborhood. Let's hope the owner gets the windows- or at least some tarps- in it before the rainy season gets rolling for real.